Siponimod-associated cystoid macular edema without known risk factors.

Purpose: This case report highlights the importance of monitoring ocular health for patients starting on siponimod treatment, a sphingosine-1-phosphate receptor modulator, for relapsing-remitting multiple sclerosis. By showing how medication adverse events present in patients, we can revisit the current guidelines on ophthalmic evaluation recommendations. Observations: We report a 60-year-old patient who presented with unilateral blurry vision upon initiating siponimod therapy for the treatment of relapsing-remitting multiple sclerosis. Her exam findings did not show visual field defects but were significant for cystoid macular edema distorting the foveal contour. Upon stopping siponimod therapy, the patient's macular edema and symptoms resolved significantly within 7 days and completely resolved 1 month later. Conclusions and importance: This case showcases siponimod-associated cystoid macular edema in a patient without known risk factors, such as diabetes mellitus and uveitis. The patient also had the earliest reported symptom onset to date following the initiation of siponimod therapy. Current recommendations from the American Academy of Ophthalmology and FDA stress the importance of ophthalmic evaluation three to four months after treatment initiation for patients with a history of risk factors. Given our current case and its comparison with four previously reported cases, we recommend that physicians inform patients of possible ocular adverse events with siponimod therapy regardless of their past medical history and duration of treatment.